Internal combustion engine



March 2o, 1934.

R.F.BRACKE INTERNAL COMBUSTION ENGINE Filed oct. 7. 1929 2 Sheets-Sheet l .March zo, 1934. R. F. BRACKE 1,951,858

INTERNAL COMBUSTION ENGINE Filed Oct. '7, 1929 2 Sheets-Sheet 2.

atented Mar.. 2G, 1934 STATES y PATENT OFFICE mesne assignments,

to Lynn A. Williams,

Evanston, and Clifford C. Bradbury, Glencoe,

Ill., successor trustees Application. October 7,

5 Claims.

My invention relates to improvements in internal combustion engines, and more particularly to engines of the two-cycle type.

An object of my invention is to provide an improved internal combustion engine.

In the present type of two-cycle internal combustion engine, wherein a fuel charge is introduced to the crank case of the engine during the compression stroke and subsequently by-passed` to the firing cylinders of the engine at the end of the ring stroke, difculties have arisen through the failure of the fuel charge from the crank case to by-pass without permitting some of the exhaust gases and at times sparks from the still burning fuel from finding their way into the crank case. Obviously this not only hinders the eicient power output of the engine but has a harmful effect upon the lubricants present in the crark case as well as the piston skirt and bearings. This undesirable condition is attributed to the existence of sub-atmospheric pressure in the crank case during and particularly at the termination of the firing stroke of the pistons. The structure which permits this condition to exist under certain operating conditions is obviously the fuel control throttle Valve interposed between the crank case and the carburetor. Usually this valve takes the appearance of the ordinary type of butterfly valve.

An'other object is to provide a two-cycle engine wherein the existence of sub-atmospheric pressure in the crank case during and particularly at the termination of the ring stroke of the pistons is rendered impossible.

A further object is to provide a two-cycle engine in which exhaust gases are thoroughly scavenged at the termination of the firing stroke.

Another object is to provide a two-cycle engine in which 4the fuel charge is admitted to the crank case in such a manner as to be evenly distributed throughout;

A further object is to provide a multi-cylinder internal combustion engine incorporating an ignition system which' positively assures simultaneous firing of the cylinders.' i

Further objects and advantages will hereinafter appear.

An embodiment of my invention is illustrated in the accompanying drawings forming a part of this application, wherein:

Fig. 1 is a sectional view of a two-cycle internal combustion engine illustrating the features of the invention;

Fig. 2 is a sectional view similar to4 Fig. 1 but 1929, Serial No. 397,802

(Cl. 12S-56) with the pistons in another of their operative positions; and

Fig. 3 is a fragmentary top plan view partially in section, illustrating the mechanism employed during the starting of the engine.

The internal combustion engine selected for illustration herein is of the well known two cylinder two-cycle portable type as may be used to propel outboard motor boats and the like.

Briefly, the engine comprises a pair of cylinders A with pistons B, a crank case C to which a fuel charge is admitted through a rotating valve D, passages E for by-passing the fuel charge from below the pistons to the cylinders A at the end of the firing strokes, exhaust ports F and spark plugs G.

The parts enumerated above comprise those found in any of the present known types of twocycle engines. My'invention contemplates the removal of the customary butterfiy throttle valve interposed between the carburetor K and the fuel induction passage J of the crank case C and the installation of a pair of buttery throttle valves H in each of the by-passes E so that there may be an unrestricted flow of the fuel charge into the crank case during the compression strokes to entirely satisfy the depression thus created in the crank case so that the existence of subatmosphere during the firing strokes is entirely precluded.

Each of the throttle valves has a radially extending arm 10 secured to the rotatably mounted shaft 11 thereof. The outer end of one arm is pivotally connected at 12 to a throttle control rod 13 adapted for manual manipulation to regulate the speed of the engine. The remaining arm 10 engages at its outer end with a slot 14 formed in a link 15, one end of which is connected at 12 to the first named arm so as to establish a lost motion connection between the second arm and the link 15.

A tension spring 16 secured at one end to the remote end of the link 15 at 17 is connected t0 the adjacent part of the arm 10 so as to normally maintain the outer end of that arm in engagement with the remote end of the slot 14.

The purpose of the aforesaid lost motion connection between the link 15 and the arm 10 is to permit the closing of its associate throttle H indef' pendently of the other throttle valve I-I by counterclockwise movement of a hand lever 20 to which a push rod 21 is pivotally connected at 22. The push rod 21 has a slot 23 extending longitudinally thereof at tne outer end, through which a pin 24 secured to the arm 10 is disposed. Thus the arm is free to move toward closing position by manipulation of the control rod 13 or by counter-clockwise movement of the hand lever 20, in which case the closing movement of but one valve is affected.

The arm 20, `which is pivoted at 30 to a bifurcated portion 31 integral with the cylinder casting, aside from serving to close the adjacent valve H when moved in a counter-clockwise direction, depresses the stern 32 of a mushroom valve 33 which opens the adjacent cylinder to atmosphere, thus rendering that cylinder inoperative and eliminating compression. The person starting the engine has therefore to overcome the compression in but the remaining cylinder, and consequently the torque required is reduced by onehalf, thus greatly facilitating the starting operation. As an additional incentive to starting, a greater quantity of the fuel charge is admitted to the operative cylinder because of its inability to pass beyond the closed valve H. When the hand lever 20 is restored to its normal position and there maintained by a tensionspring 35, the valve 33 remains seated and the adjacent throttle valve H is free to move with its companion valve upon actuation of the throttle control rod 13.

In operation, referring first ,to Fig. 1, the pistons move apart during a compression stroke, thus causing the induction of the fuel charge into the crank case C through the then open valve D from the carburetor K. As there is no restriction to this passage of fuel to the crank case, the depression created by the outward movement of the pistons is entirely satisfied by the entrance of fuel charge. As the pistons are fired and move `toward one another the fuel charge in the crank case C becomes compressed (at this time the valve D is closed) so that when they finally arrive at the position shown in Fig. 2 a relatively high condition of compression exists in the crank case, which assures the by-passing ofthe fuel through openings 40 in the piston skirts through the by-passes E and into the cylinders A. The quantity of fuel that is so by-passed of course depends upon the position of the throttle' valves. At no time during this by-passing of the fuel charge to the cylinders, however, is there a lower pressure in the crank case than that which exists in the cylinders A, and it becomes therefore impossible for exhaust gases or burning fuel to get into the crank case, as frequently occurs in the ordinarytype of two-cycle engines where a throttle valve is employed between the carburetor and the crank case. It is apparent, therefore, that thev crank case housing, the crank case bearings, wrist pin bearings and connecting rod bearings are free from attack by the harmful exhaust gases and burning fuel and that also the scavenging of the cylinders is greatly facilitated, resulting in smooth and efiicient operation as well as prolonged life of the engine.

In starting the engine, the operator will move the hand lever 20 in counterclockwise direction to entirely close the adjacent throttle valve I-I and open the valve 33 (see Fig. 3). This effectively reduces the engine torque by substantially one-half.-

The absence of a throttle valve at or near the fuel inlet orifice of the crank case C assures uniform distribution of the fuel charge in the crank case as is not always the case where a throttle valve of the butterfly type is employed, which valve by nature of its construction tends to induce the incoming fuel charge in a direction parauei with the lobes of the valve. This feature incident to the removal of the throttle valve from its ordinarily established position affords proper distribution of lubricant throughout the crank case where the lubricant is admitted as a mixture with the fuel.

Referring again to Fig. 1, I have illustrated therein an improved ignition system by means of which simultaneous firing of the opposed cylinders is accomplished by simple and eflicient means. In the past it has been customary to employ what is known as a series spark plug having two electrodes which' plugs are connected with their electrodes in series connection with the secondary of the ignition spark coil. No ground oonnection in the secondary circuit was employed.

My invention contemplates the use of the ordinary type of spark plug as shown at 50, one for each of the cylinders and each having one of its electrodes grounded to the engine casting as is peculiar to this type of plug, the remaining electrodes 51 are connected to the opposite terminals 52 of the secondary 53 of an induction coil 54. In the drawings I have shown two spark plugs so connected. Where the engine has more than two cylinders a. distributor of the secondary1 circuit may be used or two separate ignition coils, one for each pair of cylinders.

The primary circuit "of the induction coil 54 is identical to that type of circuit now employed for firing internal combustion engines and includes a timer 55 and current source 56 which usually consists of a storage or dry battery.

During the starting of the engine in the manner heretofore described the spark plug for that cylinder which is rendered inoperative by 'actuation of the lever 20 was but shunted out of the ignition circuit by a metal brush 60 which is secured to the lever 20 and is thus grounded. This arrangement is however optional at the ,will of the designer as it is contended by some authorities that the spark in that cylinder which remains operative at the starting in the manner described is made more intense than during normal operation by virtue of the relatively lower pressure which exists in the inoperative cylinder than upon 120 its atmosphere.

1. In a two-cycle internal combustion engine of the type wherein a fuel charge is admitted to the crank case thereof and compressed therein, pas- 125 sages interconnecting the crank case and the engine piston cylinders when the engine pistons are at the termination of their ring stroke, control throttle valves disposed in said passages, said valves being interconnected so as to open and 130 close simultaneously to permit fuel charges in equal amounts to by-pass from the crank case to the cylinders, and lever means for closing one of said throttle valves and for opening the cylinder associated with said valve to atmosphere, whereby 135 the engine starting torque is reduced.

2. In a multiple cylinder two cycle internal combustion engine of the type wherein a fuel charge is admited to the crank case, compressed therein and by-passed to the engine cylinder, the 14u combination of interconnected throttle valves for in dividually controlling the by-pass of fuel to each of the engine cylinders from the crank case,

a manual control for simultaneously operating said valves, an ignition circuit having spark 145 plugs associated with each cylinder, means operable for simultaneously closing one of said throttle valves and opening the cylinder associated with said valve to the atmosphere, and means associated with said last named means 150 and operated thereby for shunting the spark plug associated with said cylinder out of said ignition circuit when said cylinder is openedto the atmosphere.

3. In a multi cylinder two cycle internal combustion engine of the type having a crank case wherein fuel is compressed by engine piston movement, the combination of an unrestricted passageway for admitting fuel charges to the crank case prior to the compressing action of the pistons, throttle valves for individually controlling the by-pass of fuel to each of the engine cylinders from the crank case, each of said throttle valves having an arm connected thereto for adjusting the same, and means for simultaneously adjusting said throttle valves comprising a manipulative control rod pivotally connected to the free end of each of said arms.

4. In a multi cylinder two cycle internal combustion engine of the type having a crank case wherein fuel is compressed by engine pistonmovement, the combination of an unrestricted passageway for admitting fuel charges to the crank case prior to the compressing action of the pistons, throttle valves for individually controlling the by-pass of fuel to each of the engine cylinders from the crank case, each of said throtltle valves ha'ving an arm connected thereto for adjusting the same, means for adjusting said throttle valves comprising a rod interconnecting the free ends of each of said arms whereby said valves may be simultaneously adjusted by the manipulation thereof, and a bar connected to one bustion engine of the type having a crank case wherein fuel is compressed by engine piston movement, the combinaion of an unrestricted passageway for admitting fuel chargesto the crank case prior to the compressing action of the pistons, throttle valves for individually controlling the by-pass of fuel to each of the engine cylinders from the crank case, each of said throttle valves having an arm connected thereto for adjusting the same, means for adjusting said throttle valves comprising a rod interconnecting the free ends of each of said arms whereby said valves may be simultaneously adjusted by the manipulation thereof, a bar connected to one only of said arms, said last mentioned arm having a lost motion connection with said rod and said bar whereby one of said valves may be closed independently of the other of said valves, an air vent valve for opening to the atmosphere the cylinder associated with said last mentioned throttle valve, a lever pivoted to the head of said cylinder and connected to said bar, and a stem on said air vent valve engageable by said lever, said lever being adapted when manipulated to close one of said throttle valves and open the air vent valve for reducing the engine starting torgue. 

